The present invention relates generally to channel estimation, and more particularly, to tracking scatterer parameters used to determine channel estimates as a transmitter and/or receiver moves within a wireless channel, where the scatterer parameters characterize scattering objects in the channel.
In a wireless communication system, a transmitted signal reflects off objects (e.g. buildings, hills, etc.) in the environment, referred to herein as scattering objects. The reflections arrive at a receiver from different directions and with different delays. The reflections or multi-paths can be characterized by a path delay and a complex delay coefficient. The complex delay coefficients show fast temporal variation due to the mobility of the vehicle while the path delays are relatively constant over a large number of OFDM symbol periods.
Channel estimation is the process of characterizing the effect of the radio channel on the transmitted signal. Channel estimates approximating the effect of the channel on the transmitted signal may be used for interference cancellation, diversity combining, ML detection, and other purposes. Many channel estimation techniques in common use do not produce sufficiently accurate estimates of the channel for use by higher order modulations. Further, it is difficult to predict how the channel will change due to the mobility of the vehicle. Therefore, there is a need for new channel estimation techniques that will produce more accurate channel estimates for higher order modulation and enable channel prediction and tracking.